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Decide which constructors to report earlier.

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This gets rid of `report_individual_missing_ctors`
This commit is contained in:
Nadrieril 2024-02-06 01:21:29 +01:00
parent 924d6cd1a6
commit 3602b9d817
1 changed files with 17 additions and 19 deletions
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36
compiler/rustc_pattern_analysis/src/usefulness.rs
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@ -1319,28 +1319,16 @@ impl<Cx: TypeCx> WitnessMatrix<Cx> {
fn apply_constructor( fn apply_constructor(
&mut self, &mut self,
pcx: &PlaceCtxt<'_, Cx>, pcx: &PlaceCtxt<'_, Cx>,
mut missing_ctors: &[Constructor<Cx>], missing_ctors: &[Constructor<Cx>],
ctor: &Constructor<Cx>, ctor: &Constructor<Cx>,
report_individual_missing_ctors: bool,
) { ) {
if self.is_empty() { if self.is_empty() {
return; return;
} }
if matches!(ctor, Constructor::Missing) { if matches!(ctor, Constructor::Missing) {
// We got the special `Missing` constructor that stands for the constructors not present // We got the special `Missing` constructor that stands for the constructors not present
// in the match. // in the match. For each missing constructor `c`, we add a `c(_, _, _)` witness
if !missing_ctors.is_empty() && !report_individual_missing_ctors { // appropriately filled with wildcards.
// Report `_` as missing.
missing_ctors = &[Constructor::Wildcard];
} else if missing_ctors.iter().any(|c| c.is_non_exhaustive()) {
// We need to report a `_` anyway, so listing other constructors would be redundant.
// `NonExhaustive` is displayed as `_` just like `Wildcard`, but it will be picked
// up by diagnostics to add a note about why `_` is required here.
missing_ctors = &[Constructor::NonExhaustive];
}
// For each missing constructor `c`, we add a `c(_, _, _)` witness appropriately
// filled with wildcards.
let mut ret = Self::empty(); let mut ret = Self::empty();
for ctor in missing_ctors { for ctor in missing_ctors {
let pat = pcx.wild_from_ctor(ctor.clone()); let pat = pcx.wild_from_ctor(ctor.clone());
@ -1515,9 +1503,6 @@ fn compute_exhaustiveness_and_usefulness<'a, 'p, Cx: TypeCx>(
split_ctors.push(Constructor::Missing); split_ctors.push(Constructor::Missing);
} }
// Whether we should report "Enum::A and Enum::C are missing" or "_ is missing". At the top
// level we prefer to list all constructors.
let report_individual_missing_ctors = place.is_scrutinee || !all_missing;
// Which constructors are considered missing. We ensure that `!missing_ctors.is_empty() => // Which constructors are considered missing. We ensure that `!missing_ctors.is_empty() =>
// split_ctors.contains(Missing)`. The converse usually holds except when // split_ctors.contains(Missing)`. The converse usually holds except when
// `!place_validity.is_known_valid()`. // `!place_validity.is_known_valid()`.
@ -1526,6 +1511,19 @@ fn compute_exhaustiveness_and_usefulness<'a, 'p, Cx: TypeCx>(
missing_ctors.append(&mut split_set.missing_empty); missing_ctors.append(&mut split_set.missing_empty);
} }
// Whether we should report "Enum::A and Enum::C are missing" or "_ is missing". At the top
// level we prefer to list all constructors.
let report_individual_missing_ctors = place.is_scrutinee || !all_missing;
if !missing_ctors.is_empty() && !report_individual_missing_ctors {
// Report `_` as missing.
missing_ctors = vec![Constructor::Wildcard];
} else if missing_ctors.iter().any(|c| c.is_non_exhaustive()) {
// We need to report a `_` anyway, so listing other constructors would be redundant.
// `NonExhaustive` is displayed as `_` just like `Wildcard`, but it will be picked
// up by diagnostics to add a note about why `_` is required here.
missing_ctors = vec![Constructor::NonExhaustive];
}
let mut ret = WitnessMatrix::empty(); let mut ret = WitnessMatrix::empty();
for ctor in split_ctors { for ctor in split_ctors {
// Dig into rows that match `ctor`. // Dig into rows that match `ctor`.
@ -1540,7 +1538,7 @@ fn compute_exhaustiveness_and_usefulness<'a, 'p, Cx: TypeCx>(
})?; })?;
// Transform witnesses for `spec_matrix` into witnesses for `matrix`. // Transform witnesses for `spec_matrix` into witnesses for `matrix`.
witnesses.apply_constructor(pcx, &missing_ctors, &ctor, report_individual_missing_ctors); witnesses.apply_constructor(pcx, &missing_ctors, &ctor);
// Accumulate the found witnesses. // Accumulate the found witnesses.
ret.extend(witnesses); ret.extend(witnesses);